Liquid sample assay device

ABSTRACT

An assay device for determining the presence of specific analytes in a liquid sample comprises a container for collecting the sample liquid and a removable cap for sealing the container. The cap includes one or more test strips, such as chromatography strips, supported thereon for visually displaying the results of the assay. A chamber in the cap, collects, through an inlet, a volume of liquid from the container when it is inverted by depressing and subsequently releasing a piston located in the chamber. The liquid collected in the chamber is transferred to the chromatography strips by a wicking system. The piston frictionally engages a seal pad made of resilient material. The seal pad closes the inlet and forms a hermetic seal between the liquid contained within the container and the outside thereby preventing such liquid from becoming contaminated and any leakage of the contained liquid.

[0001] This application is a continuation in part of application Ser.No. 08/974,617, which was allowed on Jul. 26, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to liquid assay devices, and inparticular, to liquid sample containers which include a self containedmeans of assaying such liquid.

DESCRIPTION OF THE PRIOR ART

[0003] There is presently a great demand for safe, reliable and easy touse liquid assaying devices. Such devices have uses in a variety ofareas such as diagnostic testing of biological fluids, testing of watersamples, etc. An example of one such application of the device is indiagnostic and drug testing purposes of urine samples at the screeningstage. Screening apparatus are used by health practitioners as adiagnostic aid. A preliminary assay will help the practitioner todetermine the presence of various antigens in a patient's bodily liquidswhich could potentially be causing an illness. There is even a greaterdemand for such diagnostic screening apparatuses due to a widespreadfear which has been aroused in the general population by the growingnumber of people being infected with HIV. Due to the long incubationperiod of this disease many people have chosen to be screened so thatearly treatment can be obtained and the spread of this deadly diseasecan be reduced.

[0004] In society at large, there is also a growing concern about drugabuse. It is the policy of many employers to screen employees for theuse of illegal drugs. Similarly, athletes are now routinely screened forthe presence of banned substances both before and after competitions. Toaddress the need to quickly screen people for these illegal substances,various screening devices have been produced which require manualtransfer of a sample liquid from a collecting vessel to an assayingdevice. A positive test at the screening stage would require the sampleto be sealed and then forwarded to a laboratory for more rigorous andcomplete testing to verify the results of the screening test.

[0005] One such device for specifically testing for the presence ofnon-protein antigens such as most drugs of abuse is taught by U.S. Pat.No. 5,238,652. This device utilizes a thin layer chromatography membranefor testing for the presence of certain illegal drugs. The assayingdevice taught makes use of colored latex spheres combined with aspecific antibody for binding to a specific antigen (i.e. drug). Thelatex spheres are applied to a chromatography membrane upstream of animmobilized drug conjugate probe. The antibody/latex complex is pickedup by the test liquid and is used to indicate the presence or absence ofa specific antigen drug. A positive test is indicated by the absence ofa colored line in the area of the drug conjugate probe on thechromatography membrane due to the fact that the antibody will havebound the antigen rendering it unable to bind the drug conjugate probe.A negative test is indicated by a colored line corresponding to thebinding of the latex/antibody complex to the drug conjugate probe.

[0006] In use, urine drops are withdrawn manually from a collection vialand added drop-wise to a reception cavity on the device. The urine isthen absorbed by a pad and moves along the chromatography membrane bycapillary action. This particular device is problematic in that thesample liquid must be manually transferred from the collection device tothe assay device, being the chromatography membrane. This is dangerousto those conducting the assay as there is exposure to the sample whichcould include harmful materials. Also, the test sample is subject tocontamination in the transferring process which reduces the reliabilityof the assay.

[0007] U.S. Pat. No. 5,403,551 teaches an assaying apparatus which alsouses a chromatography membrane to indicate the presence or absence ofspecific antigens. As before the use of a latex/antibody complex willdisplay a colored line in the absence of a specific analyte.

[0008] This assaying apparatus comprises a collecting vessel and anassaying device as one unit. A sample is introduced into a collectingchamber which is then sealed with a cap. The sample is then introducedinto a reservoir through a flow path which is only accessible to theliquid sample when the device is inverted. The reservoir communicateswith chromatography test strips and is sized to contain only enoughsamples to wet the chromatography membranes without flooding them. Amechanical valve is operated by twisting the cap of the device in orderto close the flow path of the sample into the reservoir. In this way thesample liquid in the container is sealed off from the ambient airsurrounding the container.

[0009] This apparatus has a drawback in that it is necessary for aperson conducting the assay to remember to twist the cap and therebyclose the mechanical valve after inverting the device. A failure tocarry out this third step will result in the sample liquid in thecontainer being contaminated by impurities in the ambient airsurrounding the apparatus. This apparatus also has a further problem inthat it is possible to inadvertently close the mechanical valve prior toinverting the apparatus to start the test. This results in the test notbeing properly started upon inverting the apparatus. The operator willthen waste time waiting for the test to begin before realizing that thevalve has been closed. The structure taught by U.S. Pat. No. 5,403,511suffers from a further drawback in that it is complicated, involvingseveral structural parts. This apparatus is therefore difficult andexpensive to manufacture.

[0010] As such, there is a need for an assaying apparatus transferred toan assaying device included in the apparatus, without having to removethe sample liquid from the apparatus. A device is needed which has anautomatic shut-off valve for preventing contamination of the sampleliquid after the assay has been commenced. The automatic properties ofsuch a valve would effectively eliminate the potential for human errorin operating such a valve.

[0011] There is also a need for a simpler assaying device which iseasier and less expensive to manufacture, which accomplishes thefunction of transferring liquid from a collecting medium to an assayingsystem without having to manually transfer the sample liquid, therebyexposing the sample liquid to the external environment.

SUMMARY OF THE INVENTION

[0012] The present invention is an apparatus, having an assaying devicefor conducting an assay on a sample liquid. The apparatus has means forcollecting a sample liquid and means for transferring a predeterminedvolume of the collected sample liquid to the assaying device. Theapparatus has an automatic valve for sealing the sample liquid in theapparatus from the external environment after the assay has beencommenced.

[0013] According to one aspect of the invention, an apparatus isprovided for conducting an assay on a sample liquid. The apparatusincludes a container defining a chamber, the container having an openend for collecting a sample liquid. The apparatus has a removable capfor closing the container. An assaying device is included in theapparatus located on one of the cap and the container for visualobservation thereof, the assaying device leaving means for receiving andchemically analyzing the sample liquid and visually displaying thepresence of a specific analyte in the sample liquid. The apparatusfurther includes a defines a sub-chamber communicating with the assayingdevice. The reservoir has a wall which defines at least one openinglocated to collect a predetermined volume of sample liquid inside thesub-chamber upon submerging the reservoir in the sample liquid in thecontainer. The apparatus also includes a valve member which is locatedbetween the reservoir sub-chamber and the assaying device, the valvemember is formed of a material that absorbs sample liquid and swellsthereby closing off the assaying device from the sub-chamber.

[0014] According to another aspect of the invention, there is providedan apparatus for conducting an assay on a liquid located in a container.The apparatus comprises a cap for closing the container. The apparatusincludes an assaying device located on the cap for visual observationthereof. The assaying device has means for receiving and chemicallyanalyzing a sample liquid and visually displaying the presence of aspecific analyte in the sample liquid. A reservoir is attached to thecap. The reservoir defines a chamber communicating with the assayingdevice, the reservoir having a wall defining at least one openinglocated to collect a predetermined volume of sample liquid inside thechamber upon submerging the reservoir in the sample liquid. Theapparatus has a valve member located between the reservoir chamber andthe assaying device, the valve member being formed of a material thatabsorbs sample liquid and swells thereby closing off the assaying devicefrom the chamber after a predetermined amount of sample liquid isreceived by the assaying device.

[0015] According to another aspect of the invention there is provided amethod of conducting an assay on a liquid comprising the step ofproviding a container for collecting a liquid sample to be assayed. Themethod includes the further step of segregating a predetermined amountof the liquid to be assayed from the remainder of the collected sampleliquid by providing a barrier between the predetermined amount of liquidand the remainder of the collected sample liquid, the barrier beingexpandable upon contact with the liquid. The method includes the furtherstep of contacting the predetermined amount of liquid with an assayingdevice including a chromatography strip having means for chemicallyanalyzing a liquid for a specific analyte. The method includes thefurther step of expanding the barrier to hermetically seal off theremainder of the collected liquid.

[0016] According to another aspect of the present invention, there isprovided an apparatus for conducting an assay on a liquid located in acontainer. The apparatus comprises a cap for closing the container. Theapparatus includes an assaying device located on the cap for visualobservation thereof. The assaying device has a means for receiving andchemically analyzing a liquid sample and visually displaying thepresence of a specific analyte in the sample liquid. The cap furtherincludes a chamber defined by an inner and outer wall, attached to thecap and communicating with the assaying device. The chamber furtherincludes a piston positioned with the chamber and an inlet for providinga passage to collect a volume of sample liquid inside the chamber. Thepiston contacts the inner wall of the chamber and moves between a firstoperating position where the inlet is sealed, and a second operatingposition where said inlet is open and allows for the collection ofsample liquid is said chamber upon submergence. The cap further includeswicking system for supplying the liquid collected in said chamber to theassaying device. A valve member or seal pad comprising a generallyannular disc forms a seal on the inlet. A frictional fit between thepiston and the seal pad ensures that the movement of the piston effectsthe movement of the seal pad. A second seal maintains contact betweenthe piston and said chamber wall such that when the container isinverted the seal prevents the leakage of liquid from the chamber.

[0017] According to yet another aspect of the invention, there isprovided a method of conducting an assay on a liquid comprising the stepof providing a container for collecting a liquid sample to be assayed.The method includes the further step of segregating a predeterminedamount of the liquid to be assayed from the remainder of the collectedsample liquid by providing a seal between the portion amount of liquidand the remainder of the collective sample liquid. Wherein the methodfor segregating this portion of liquid includes inverting the containerand depressing the piston within the chamber thereby moving the seal padaway from the inlet and the closed position, to the open positionthereby evacuating the air from the chamber. The piston is then releasedand in turn allows liquid sample to enter the chamber through the inletthrough both gravity and suction. The piston returns to the firstoperating thereby closing the inlet. The container is then returned toan upright position. The method includes the further step of contactingthe predetermined amount of liquid with an assaying device including achromatography strip having means for chemically analyzing a liquid fora specific analyte.

[0018] In another embodiment, the invention provides an assay device fora liquid contained within a container, the device comprising a removablecap for the container, the cap having:

[0019] a reservoir to receive a sample of the liquid from the container;

[0020] a passage for transferring the sample of liquid from thecontainer to the reservoir;

[0021] a means for closing the passage;

[0022] a means for assaying the liquid sample;

[0023] a means for transferring the liquid sample from the reservoir tothe means for assaying.

[0024] More particularly, the invention provides in one embodiment anassay device for a liquid contained within a container, the devicecomprising a removable cap for the container, the cap having:

[0025] a reservoir to receive a sample of the liquid from the container;

[0026] a passage for transferring the sample of liquid from thecontainer to the reservoir;

[0027] a valve for closing the passage;

[0028] a plurality of chromatographic test strips for assaying theliquid sample;

[0029] a wick for transferring the liquid sample from the reservoir tothe test strips.

[0030] The invention also provides a method of using such device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other features of the preferred embodiments of theinvention will become more apparent in the following detaileddescription in which reference is made to the appended drawings wherein:

[0032]FIG. 1 is a perspective view of a preferred embodiment of anapparatus according to the present invention;

[0033]FIG. 2 is an exploded perspective view of the cap used in theapparatus of FIG. 1;

[0034]FIG. 3 is a cross-sectional view of the apparatus taken alonglines 3-3 of FIG. 1 depicting the apparatus in a first operatingposition;

[0035]FIG. 4 is a cross-sectional view of the apparatus taken alonglines 3-3 of FIG. 1 depicting the apparatus in a second operatingposition;

[0036]FIG. 5 is a cross-sectional view of the apparatus taken alonglines 3-3 of FIG. 1 depicting the apparatus in a third operatingposition; and

[0037]FIG. 6 is an enlarged cross-sectional view of a portion of the captaken along lines 3-3 of FIG. 1 the apparatus in a fourth operatingposition;

[0038]FIG. 7 is a side cross sectional view of a further embodiment ofthe invention;

[0039]FIG. 8 is a bottom view of the embodiment of FIG. 7;

[0040]FIG. 9 is a plan view of the middle portion of the embodiment ofFIG. 7;

[0041]FIG. 10 is a plan view of a test strip for the embodiment of FIG.7;

[0042]FIG. 11 is a side elevation of the test strip of FIG. 10;

[0043]FIG. 12 is a plan view of the embodiment of FIG. 7 illustratingthe cover portion;

[0044]FIG. 13 is a side cross sectional view through A-A of FIG. 9;

[0045]FIG. 14 is a side cross sectional view of the seal pad of FIG. 7;

[0046]FIG. 15 is a front view of the pad of FIG. 14;

[0047]FIG. 16 is a perspective view of the embodiment of FIG. 7;

[0048]FIG. 17 is a side cross-sectional view of a further embodiment ofthe invention; and

[0049]FIG. 18 is a plan view of the embodiment of FIG. 17 cut along line1-1 illustrating the cover portion;

[0050]FIG. 19 is a plan view of the embodiment of FIG. 17 illustratingthe valve member in a alternative position;

[0051]FIG. 20 is a plan view of the embodiment of FIG. 17 cut along line2-2 illustrating the cover portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] Referring to the drawings, an apparatus according to the presentinvention is generally indicated by numeral 10 as shown in FIGS. 1 to 3.Apparatus 10 includes a container 25 which defines a chamber 33. Thechamber 33 functions to hold a quantity of a sample liquid 30 asdepicted in FIGS. 3, 4 and 5.

[0053] Apparatus 10 includes a removable cap 7 which screws onto thecontainer 25 in order to close the container. Preferably, the containerhas screw threads formed into it near an opening at the top of thecontainer. The cap has a cylindrical portion 8 which extends downwardlyfrom a bottom central portion of the cap. The cylindrical portion 8 ismolded to the cap to form a single molded part including the cap and thecylindrical portion 8. In an alternate embodiment the cylindricalportion and the cap can comprise two separate parts which are tightlyattached together.

[0054] A reservoir 18 is attached to a bottom surface of the cap whenthe cap 7 is screwed onto the container 25, the reservoir 18 defines asub-chamber 23 in the chamber 33 as shown in FIGS. 3, 4 and 5. Thecylindrical portion 8 of the cap 7 is located in the sub-chamber. Thereservoir has four openings 20 formed in a wall 21 of the reservoir 18.The openings 20 are of a sufficient size to allow a sample liquid 30 toflow into the reservoir 18 when the reservoir is submerged in the sampleliquid 30. It is possible to have one or more openings 20 in the wall 21of the reservoir. A greater number of openings will increase the rate atwhich liquid will flow into the sub-chamber 23 upon submerging thesub-chamber in the sample liquid in the container. Similarly the rate atwhich the sample liquid will flow out of the sub-chamber through theopenings 20 will be proportional to the number of openings and the sizeof the openings formed in the wall 21.

[0055] The openings 20 on the reservoir wall 21 are located at a commonlevel with respect to a base 22 of the reservoir 18. It is not necessarythat the openings 20 all be at the same level on the wall 21 withrespect to the base 22, and other embodiments are possible where theopenings are at varying levels on the wall 21 with respect to the base.However, the location of the opening 20 nearest to the base 22 willdetermine the ultimate level of the sample liquid 30 which will becollected in the sub-chamber 23 after inverting the apparatus, asdiscussed in more detail below. Hence, it is possible to predeterminethe amount of sample liquid which will be collected in the sub-chamber23, upon submersion of the reservoir in the sample liquid, by selectingthe location of openings 20 on the wall 21. By placing the openingsfurther upwardly from the base 22, more sample liquid will be collectedin the sub-chamber 23. Conversely, less liquid will be collected in thesub-chamber when the openings 20 are located closer to the base 22. Aswill be discussed below, the volume of liquid collected in thesub-chamber will also be related to the air pressure which within thereservoir 18 during filling of the sub-chamber.

[0056] The openings 20 are positioned on the wall 21 relative to thebase 22 such that a volume of sample liquid will be collected in thesub-chamber 23 which will be sufficient to allow the assay to beconducted reliably. However, the volume of sample liquid collected willbe sufficiently small so that an assaying device will not become floodedthereby adversely affecting the test results.

[0057] The reservoir 18 is attached to the cap 7. Many methods ofattachment known in the art are possible for attaching the reservoir tothe cap. The cylindrical portion 8 of the cap 7 has a plurality ofpassageways 14 formed therein (see FIG. 1). These passageways 14 extendfrom a bottom end of the cylindrical potion 8 of the cap through a topsurface the cap 7.

[0058] At least one liquid permeable wick 3 is provided for transportingthe sample liquid through the passageway 14. The wicks 3 transport thesample liquid 30, by capillary action, from the reservoir to a pluralityof wick pads 4, as discussed in more detail below. The wicks 3 areformed of a cellulose based porous material, such as cellulose fiberswhich allows an aqueous liquid to be absorbed by the wicks and movethrough the wicks 3 by capillary action. Alternate embodiments arecontemplated where the wicks are formed of other materials which willabsorb and transport a liquid through capillary action.

[0059] The wicks are impregnated with colored latex spheres for thepurpose of conducting an assay which is explained below. Since thematerial with which the wicks are impregnated is assay specific,alternate embodiments are contemplated in which the wicks areimpregnated with materials other than latex spheres for the purposes ofconducting different assays. Depending on the assay being performed inan alternate embodiment, it may not be necessary to impregnate the wickswith any material.

[0060] As discussed below, the composition of the wicks is dependentupon the type of tests being conducted on the sample. If only a singletype of test is being conducted, it will be understood that only onewick would be required. Similarly, one wick can be used to supply liquidto a plurality of test strips. In such case, the cylindrical portion 8would require only one passageway 14 located, preferably, in the centerthereof.

[0061] An indentation 12 is formed over each of the passageways 14 onthe top surface of the cap 7. The indentations 12 are each sized toaccept a wick pad 4 which is formed of a non-woven glass fiber materialthrough which the sample liquid will move by capillary faction. The wickpads 4 are located adjacent to the assaying device which may comprise aplurality of known liquid test strips 5, and function to draw liquid upthrough the wicks 3 and to transfer sample liquid 30 to the test strips5 which are located on the cap 7, as discussed further below. Othermaterials which can absorb and transfer a liquid via capillary actioncan comprise the wick pads in alternate embodiments. A perimeter wick 6is located in a groove 9 on the top surface of the cap. The perimeterwick is comprised of a liquid absorbent material such as cellulose paperand is located adjacent to the test strips 5. The perimeter wick 6functions to absorb sample liquid 30 from the test strips 5 therebydrawing the sample liquid 30 along the test strips 5. Further, perimeterwick 6 also serves to prevent the strips 5 from being flooded by theliquid being assayed. A wicking system comprising the wicks 3, the wickpads 4 and the perimeter wick 6 provides transferring means fortransferring sample liquid 30 from the reservoir 18 to the test strips5.

[0062] A valve member 15 is located adjacent to the base 22 of thereservoir 18, inside the sub-chamber 23. The valve member 15 is locatedadjacent to the cylindrical portion 8, and therefore the valve member 15is located adjacent to the wicks 3. When the valve member is in a valveopen position, a gap 35 exists between the cylindrical portion 8 of thecap and the valve member 15, as indicated in FIGS. 3 and 5.

[0063] The valve member 15 is formed of a cross-linked polymer which ishydrophilic. In one embodiment, the cross-linked polymer comprising thevalve member is chosen from the family of polymers known as polyetherblock amides available from ATOCHEM under the trade-mark PEBAX. Othercross-linked polymers which are hydrophilic and which swell uponabsorbing water could also be used to comprise the valve member. It isnot necessary that the material comprising the valve member be across-linked polymer. Any material which absorbs liquid and swells andthus prevents further flow of sample liquid through cylindrical portion8, can comprise the valve member in alternate embodiments of theinvention. Other materials are also possible for the valve memberdepending upon the liquid being tested and the substance being assayed.For example, PEBAX functions sufficiently well with aqueous liquids.However, this material has been shown to absorb the active ingredient inmarijuana, THC, and, therefore, a device using such valve would give afalse negative result. A valve made from balsa wood on the other handcan also be used for aqueous liquids and does not bind with THC.

[0064] Other embodiments of the invention are contemplated which includea valve member constructed of a lyophilic sol or gel which can absorbeither aqueous solvents or non-aqueous organic solvents. In either case,absorption of the liquid will result in swelling and closing of thevalve member. Hence, materials which swell upon absorbing an oil basedor organic liquid and which are impermeable to these liquids when fullyswollen, can comprise the valve member in alternate embodiments. Inanother embodiment, the valve member 15 is made of a laminate having anexpanding layer of balsa wood and a sealing layer of a polymer such ascross linked polyolefin. The choice of balsa wood is preferred in thecase of aqueous liquids and where materials discussed above may bindwith the analytes being tested for.

[0065] The valve member 15 according to one embodiment of the presentinvention will absorb a water-based sample liquid 30 such as urine. Uponbeing submerged in the sample liquid the valve member will beginabsorbing sample liquid 30. The valve member will swell gradually to amaximum expansion. This maximum expansion will be reached inapproximately ten minutes. The valve member 15 is in a valve openposition prior to the absorption of any liquid by the valve member 15.Before the valve member 15 has swelled to its maximum expansion, the gap35 is present between the valve member 15 and the wicks 3. As such,sample liquid in the reservoir 18 will come into contact with the wicks3 when the valve member is in the valve open position. When the valvemember 15 has absorbed a sufficient amount of sample liquid to swell toits maximum expansion the valve member 15 will reach a valve closedposition thereby closing the gap 35 as depicted in FIG. 6.

[0066] The valve member 15 serves various functions in the device. Forexample, when the valve member is in the valve closed position, ithermetically seals the sample liquid 30 in the chamber 33 and in thesub-chamber 23, from the ambient air outside of the apparatus 10. Thisprevents any contamination of the sample liquid located in the chamber33, which may be required for testing at a later time. Such furthertesting may be required in the event that the results of the presenttesting device are to be verified. Such a hermetic seal, also preventsany more sample liquid from the reservoir from coming into contact withthe wicks 3. As such, the movement of any sample liquid, remaining inthe sub-chamber 23, to the test strips 5 is halted. Such sealing is alsorequired in an embodiment of the invention where an air outlet isprovided on the top surface of the cap. Such outlet is provided torelieve any pressure which may accumulate as the liquid is transportedacross the test strip. As will be appreciated, in an embodiment as shownin the figures, such pressure accumulation will occur along the outerperimeter of the cap. Therefore, the outlet would preferably comprise agap along such outer perimeter. It will also be appreciated that suchpressure may be quite minimal and, therefore, an outlet as described isrequired only as a contingency basis.

[0067] In another embodiment of the invention, the air outlet maycomprise one or more holes (not shown) in the reservoir 18. Such holeswill be designed such as to permit the passage of air therethrough whilebeing small enough to prevent the passage of liquid. It will beappreciated that the sizing of such holes will be dependent upon thesurface tension of the liquid being tested. It will also be appreciatedthat if such holes are provided in the reservoir 18, no additional airoutlets would be required in the cap thereby resulting in the devicebeing completely sealed without any leakage of the contents.

[0068] The valve member also functions to prevent any sample liquid inthe container from being suctioned out of the container when theapparatus is stored in a low pressure compartment. This would otherwisebe problematic in situations such as where the apparatus is stored inthe cargo bay of an aircraft upon shipment of the apparatus to alaboratory for further testing. To relieve the pressure differentialbetween the outside of the container and the inside of the container, itis contemplated to place a small pressure equalizing opening in the capabove the test strips, in an alternate embodiment. In such a case, anovercap could be placed above the cap.

[0069] In another alternate embodiment, it is contemplated to laminate atop surface of the valve member with a rubber or a lacquer coating inorder to prevent the valve member from drying out in arid conditions.

[0070] A plurality of test strips 5 are located on the cap 7 and arethus readily visible. The test strips 5 provide an assaying devicelocated on the cap of the container for visual observation thereof. Inan alternate embodiment, as described below, the test strips 5 can belocated on the container 25. The test strips 5 may comprisechromatographic, chemi-fluorescent or other known liquid assay strips.The test strips 5 have means for receiving the sample liquid 30. Themeans for receiving the sample liquid are ends of the test strips 5which are in direct contact with the wick pads 4. In one embodiment, thetest strips conduct chromatographic assays and four separatechromatography membranes 38 are provided on the cap. Each of the fourchromatography membranes 38 comprise two chromatography strips 5. Hencethere are eight chromatography strips 5 allowing for eight separateassays to be conducted on a sample liquid. Hence, it is possible to testfor the presence of several different substances at the same time, whileeight chromatography strips are shown in FIG. 1, a greater or lessernumber of individual strips may be used depending on the desired numberof tests to be run on the sample liquid 30. The chromatography membranes38 are composed of a porous material through which the sample liquidwill move by capillary action. Preferably the chromatography membranesare composed of a cellulose nitrate material.

[0071] Each of the chromatography strips 5 is impregnated with a testantigen conjugate probe which is immobilized at a fixed location on thechromatography strip 5. The test chemical structure to the specificantigen, such as cocaine or heroin, which is being tested for by thatparticular chromatography strip 5. A test antigen conjugate probe is amolecule having the same or similar chemical structure as the substancewhich is being tested for. The active site on a conjugate probe willgenerally be anchored to a larger molecule but will be available to bindall antibody which has been sensitized to the antigen for which the testis being directed.

[0072] A second probe, or control or test valid probe, is immobilized ata location downstream on the chromatography strip 5 of the test antigenconjugate probe. The second probe is a protein antigen conjugate probe.The antibodies are sensitized to have a second site which will bind theprotein antigen conjugate probe. As mentioned previously, the wicks 3are soaked in latex which consists of colored microscopic latex sphereswhich are coated with the antibodies sensitized to bind the specificantigen and the protein antigen conjugate probe. The latex spheres maybe about 0.1 to about 1 micron in diameter and may be one of manycolors. The spheres are only visible when concentrated together in largenumbers. The latex spheres are impregnated on the wicks 3 such that theyare immobilized prior to coming into contact with the sample liquid 30.As the sample liquid moves along the wicks 3, the sample liquid 30 willeventually come into contact with the latex spheres. The latex spheresbecome mobilized upon coming into contact with the sample liquid 30 andare carried with the sample liquid as the sample liquid moves along thewicks, through the wick pads, and eventually along the chromatographystrips 5.

[0073] If the sample liquid contains none of the specific antigen beingtested for, then the antibodies attached to the latex spheres will bindthe test antigen conjugate probe thereby forming a complex consisting ofthe test antigen conjugate probe and the latex spheres at the site ofimpregnation of the test antigen conjugate probe on the chromatographystrip 5. This will give rise to the appearance of a colored line at thesite of impregnation of the test antigen conjugate probe.

[0074] The remaining latex spheres which pass the test antigen conjugateprobe after the binding sites on the test antigen conjugate probe havebecome saturated, will bind to the protein antigen conjugate probelocated further downstream along the chromatography strip 5. This willgive rise to a second colored line at the site of impregnation of theprotein antigen conjugate probe. The purpose of the second colored lineis to indicate that the test is active. Hence a negative test will giverise to two colored lines on the chromatography strip.

[0075] In the event that the test antigen is present in the sampleliquid 30, then the antibodies on the latex spheres will bind to thetest antigen molecules immediately upon the sample liquid coming intocontact with the latex spheres on the wick 3. The active site on theantibody for binding the test antigen will then not be available forbinding the test antigen conjugate probe on the chromatography strip 5.As such, the latex spheres will pass over the site of impregnation ofthe test antigen conjugate probe. As a result, no line will be formed atthat site. The antibodies will however, bind to the protein antigenconjugate probe further downstream to indicate that the test is active.Hence, a positive test will be indicated by the presence of a singlecolored line located at the site of impregnation of the protein antigenconjugate probe on the chromatography strip 5.

[0076] It should be appreciated that an immunoassay can be conductedwith substances other than latex spheres. One alternative is to usecolloidal gold particles in the place of latex spheres. It will beappreciated to those knowledgeable in the art that many different typesof assays may be conducted with the apparatus 10 which may or may not beimmunoassays as described above. Such assays will depend on the teststrips used.

[0077] In the above example, a plurality of test strips are provided onthe device. In another embodiment, designed for a specific application,only one test strip may be required. An example of such embodiment is anassay device designed for testing the presence of a particular substancein water or urine samples.

[0078] A transparent protective cover 2 is placed over thechromatography strips 5 on the cap 7 in order to provide a protectivebarrier for the chromatography strips to prevent them from becomingcontaminated by substances which may be suspended in the ambient airsurrounding the chromatography strips. A label 1 is placed over theprotective cover 2 for indicating which specific antigen is being testedfor on each individual chromatography strip 5. The label also functionsto emphasize the results of the assay. The label has a plurality ofopenings 16 corresponding to the area on each chromatography strip 5where the test antigen conjugate probe has been impregnated. Hence theappearance of a colored line at this site will be emphasized by anopening 16 on the label 1. A second group of openings 17 is formed inthe label along the periphery of the label. Openings 17 overlap with thesections of the chromatography strips 5, which have been impregnatedwith the protein antigen conjugate probe. The openings 17 will emphasizethe appearance of a colored band at this location on the chromatographystrips 5 thereby indicating that the test is active.

[0079] In an alternate embodiment, the cover 2 and the label 1 cancomprise a single integrally formed part. To achieve this result, thelabel could be silk screened or otherwise embossed onto the cover. Othermethods known in the art are also possible for imprinting the label ontothe cover.

[0080] To operate the apparatus 10, it is necessary firstly to removethe cap 7 from the container 25. The individual being tested will thenfill the chamber 33 with a sample liquid which would normally be urine.Preferably, chamber 33 will be filled to approximately half of itsvolume with sample liquid 30. Once the chamber 33 has been filled withsample liquid, the cap 7 is screwed on tightly to the container 25 sothat a hermetic seal is formed between the container 25 and the cap 7.The apparatus, in a first operating position, after the initial fillingof the chamber 33 with sample liquid 30 with the cap 7 securely attachedto the container 25, is depicted in FIG. 3. It is apparent that thereservoir 18 defines a sub-chamber 23 in the chamber 33. At this stageof operation, the valve member 15 is in the valve open position. A gap35 exists between the valve 15 and the wicks 3 which are supported inthe cylindrical portion 8 of the cap.

[0081] After the chamber 33 has been filled with sample liquid 30, it isthen necessary to screw the cap onto the container and then to invertthe apparatus in order to submerge the reservoir 18 in the sampleliquid, in the chamber 33. FIG. 4 depicts the apparatus in an invertedposition. The reservoir 18 is submerged in the sample liquid 30 upon theinversion of the apparatus 10. The sample liquid 30 enters into thereservoir through the openings 20 in the wall 21 of the reservoir 18. Asthe level of the sample liquid 30 in the reservoir sub-chamber 23 risesabove the level of the openings 20, air in the sub-chamber 23 can nolonger escape out of the sub-chamber through the openings 20. As such, apressure-head is created between the rising sample liquid in thesub-chamber 23 and the air between the sample liquid 30 and the base 22of the reservoir 18. The pressure-head created prevents the level ofliquid in the inverted sub-chamber 23 from rising to a level sufficientto allow the wicks 3 to come into contact with the sample liquid 30. Assuch, the 25 assay will not begin while the apparatus is in the invertedposition. At this stage, the valve member 15 is also not brought intocontact with the sample liquid 30, hence the valve member 15 will notyet begin to swell thus remaining in the valve open position. As suchthere is still a gap 35 between the wicks 3 and the valve member 15.

[0082] As will be appreciated by those skilled in the art, the pressurehead discussed above also forces the air within the reservoir throughthe wick 3 while the valve is still in the open position. The rate ofsuch air passing through the wick will be dependent on thecharacteristics of the wick material such as its porosity and on thenumber of wicks present.

[0083] It will be understood that if the apparatus is maintained in theinverted position too long, enough air will be passed through the wickto allow the liquid level within the sub-chamber 23 to reach the bottomof the wick. In such case, the assay may commence prior to righting thecontainer which may not be desired. Further, if the liquid is permittedto enter the wicks while the container is inverted and if such containerincludes an externally venting air outlet as described above, leakage ofthe liquid may result. For an apparatus as described herein, the timeinverted is approximately fifteen to thirty seconds.

[0084] After maintaining the apparatus in the inverted position for thetime mentioned above, a predetermined amount of liquid is collected inthe sub-chamber 23, the apparatus is then reverted to the uprightposition as shown in FIG. 5. As mentioned above, the maximum time formaintaining the apparatus in such inverted position is dependent uponthe porosity of the wick. The level of liquid retained in thesub-chamber will depend on the level of the openings 20 on the wall 21of the reservoir 18, as excess sample liquid in the reservoir 18 willflow out of the sub-chamber 23 through openings 20. Hence the level ofliquid remaining in the sub-chamber 23 after reversion of the apparatuswill be determined by the location of the opening 20 on the wall 21nearest to the base 22 of the reservoir. The predetermined volume ofsample liquid collected inside the sub-chamber 23 is the volume ofsample liquid remaining in the sub-chamber after the sample liquid hasfiltered out of openings 20 upon reversion of the apparatus to theupright position.

[0085] After returning the apparatus to its upright position, the valvemember 15 becomes submerged in the sample liquid 30. Also, the gap 35becomes filled with sample liquid bringing the wicks 3 into contact withthe sample liquid thereby commencing the transfer of sample liquid tothe chromatography strips. Once the valve member 15 becomes submerged inthe sample liquid it begins to gradually absorb sample liquid and toswell. The valve member 15 will eventually seal off the gap 35. However,the valve will swell slowly enough so that the gap 35 will not be sealedby the valve 15 until the predetermined volume of liquid collected inthe reservoir has been absorbed by wicks 3. The predetermined amount ofsample liquid, received by the assaying device before the valve memberseals off the sub-chamber 23 from the assaying device will be determinedby selecting the amount of sample liquid which can be collected by thesub-chamber 23 upon submerging it in the sample liquid in the chamber33, as described above.

[0086]FIG. 6 depicts the valve member 15 in its fully expanded positionwhere the valve member has closed gap 35 forming a hermetic seal betweenthe reservoir sub-chamber 23 and the wicks 3. As such, a hermetic sealis formed between the sample liquid in chamber 33 and the ambient airoutside the apparatus 10 so that the sample liquid 30, which may besubject to further testing, cannot be contaminated after the assay hasbeen completed.

[0087] The reservoir 18, upon inverting the apparatus 10 and thenreverting the apparatus to its upright position, serves to segregate apredetermined amount of liquid to be assayed from the remainder of thecollected sample liquid by providing a barrier between the predeterminedamount of liquid and the remainder of the collected sample liquid. Thebarrier includes the valve member and it may be attached to the base ofthe reservoir. The barrier is therefore expandable upon contact with theliquid. The wicks 3 and the wick pads 4 provide means for contacting thepredetermined amount of liquid with an assaying device including achromatography strip having means for chemically analyzing a liquid fora specific analyte. The liquid absorbing and swelling properties of thevalve member provides means for expanding the barrier to hermeticallyseal off the remainder of the collected sample liquid.

[0088] According to another embodiment of the present invention, thechromatography strips 5 which constitute the assaying device can belocated on a sidewall 44 of the container 25 as indicated by strips 5shown in chain-dotted lines in FIG. 5. In this embodiment, the sidewall44 has cylindrical portion 8′ extending into the chamber 33. Attached toan interior surface of the sidewall 44 of the container 25 over thecylindrical portion is the reservoir 18′. As with the preferredembodiment, the cylindrical portion 8′ defines a plurality ofpassageways 14′, each passageway 14′ supporting a wick which will extendfrom the reservoir sub-chamber 23′ to the chromatography strips 5′. Thisembodiment is operated by first tilting or inverting the apparatus 10and then placing the apparatus on its base 42 or can a side of thesidewall opposite to the section of the sidewall to which the reservoir18′ is attached, so that excess sample liquid can flow out of thereservoir sub-chamber after it has been submerged in the sample liquid.If the apparatus is to be placed on its side after submerging thereservoir, the openings 20 in the reservoir would be in the sidewall 21′of the reservoir. However, if the apparatus is to be placed on the baseof the container after submersion of the reservoir then the openings inthe reservoir will be in the base 22′ of the reservoir as indicated inFIG. 5. A valve member 30′ is located in the reservoir sub-chamberbetween the cylindrical member 8′ and the base 22′ of the reservoir.

[0089] In yet another embodiment of the present invention, thechromatography strips 5 can be located on the base 42 of the apparatus10. This embodiment would be like FIG. 4, but the cap would be enlargedand become the container, and the container would perform the functionof the cap. To operate this embodiment, one would fill the containerwith sample liquid and then seal the container by putting on the cap.Inverting the apparatus would then allow the assay to proceed tocompletion as described above. The apparatus is not reverted to theupright position.

[0090] It will be appreciated by those skilled in the art that theapparatus 10 can be used for many applications other than screeningbodily liquids for specific antigens. Among other applications, theapparatus cart be used to test water samples from lakes and rivers forvarious pollutants. Also, an alternate embodiment of this invention canbe used to test organic liquids such as oil samples for the presence oftoxins such as PCBs.

[0091] A further embodiment of the present invention is illustrated inFIG. 7. As with the embodiments discussed previously, the assayingdevice includes a container (not shown) as described above. A cap forthe container is shown generally at 100. The cap 100 includes a base 102preferably having a thread 104 for engaging a corresponding thread onthe container as described above. The cap 100 further includes a middleportion 106 and a cover 108. The base 102 includes a bottom wall 113which defines the bottom wall for a reservoir or well 110 for receivinga sample of the liquid contained within the container. Such sample ofliquid is shown at 111. The base 102 also includes a liquid inletportion 112. As shown in FIGS. 7 and 8, the inlet portion 112 ispreferably rectangular in plan view and triangular in cross section. Theinlet portion 112 includes a plurality of windows 114 on a side wall 116thereof. The windows 114 allow liquid from within the container into thewell 110. As will be explained below, in the preferred embodiment, thewindows 114 are located approximately mid way along the height of theside wall 116 in order to permit a sufficient volume of the liquid to becollected within the well 110.

[0092] As shown in FIGS. 7 and 9, the middle portion 106 of the capincludes a bottom wall 115 which defines a top wall for the well 110.The middle portion 106 also includes an elongate wick chamber 118containing a wick 120. The wick chamber 118 is located proximal to theouter diameter of the cap 100. The bottom portion of the chamberincludes an opening from which depends a plurality of bars 119preferably of a “U” shape which supports the wick 120. This arrangementis shown in FIG. 13. The opening in the bottom of the chamber 118allowing the wick 120 to contact the sample of liquid 111 within thewell 110 while the bars 119 maintain the wick in a fixed position. Thewick 120 is made of a material which absorbs the liquid sample andtransfers same by capillary action. Wick 120 is preferably in the formof a rectangular slab which extends across the length of the chamber118. The appropriate material for the wick is dependent upon the liquidsample and the type of tests being conducted. The possible materialswhich can form the wick were discussed above.

[0093] The middle portion 106 supports, on the top surface 122, aplurality of test strips 124 for conducting the desired assays. As bestshown in FIGS. 10 and 11, the test strips 124 include assay surface 126and first and second wick pads 128 and 130, respectively. The assayssurface 126 of the test strip are conventional and are treated withvarious reagents depending upon the assay being conducted. Variousconventional forms of test strips are possible for use in the presentinvention. Examples of such strips are provided above. In the usualcase, the test comprises a chromatographic assay for the presence of aparticular analyte in the liquid. In a preferred embodiment, the stripsinclude an assay region 127 and a control region 129. The assay region127 is provided with the reagents discussed above for conducting thedesired assay. The control region 129 is provided with differentreagents for ensuring that the test was conducted properly in that asufficient volume of liquid was absorbed and contacted with thereagents. The test strips are made of an appropriately absorbentmaterial which draws liquid across its surface thereby bringing suchliquid into contact with the various reagents. By providing the assaydevice with a plurality of different test strips, various assays can beconducted simultaneously on a given sample. In one embodiment as shownin FIG. 11, the wick pads 128 and 130 are provided below the assaysurface 126. In another embodiment, such wicks can be provided above theassay surface. In such case, the first wick 128 functions as a bridgelinking the wick 120 to the assay surface 126 of the test strip 124.

[0094] Wick pads 128 and 130 are contained within first and secondrecesses 132 and 134 on the upper surface of the middle portion 106.First recess 132 is located above and opens into the wick chamber 118.In this manner, first wick pad 128 contacts the wick 120 and is wettedby same thereby drawing such liquid. In such manner, liquid 111 from thewell 110 is supplied to the first wick pad 128 which then transfers theliquid to the test strip which, in turn, transfers the liquid to thesecond wick pad 130 where it is collected. In the preferred embodiment,second wick pad 130 for each test strip is provided proximal to theouter diameter of the cap 100 and opposite from the first wick pad 128.In this way, the length of the test strips is maximized over the surfaceof the cap 100. Second wick pad 130 draws liquid along the length of thetest strip 124 and prevents flooding of same.

[0095] It will be understood that test strips as described above aregenerally known in the art. Accordingly, a variety of test strips can beutilized in the present invention. Such strips can, for example, be of achromatographic or a chemi-luminescent assay nature, and can be used totest for a variety substances in either aqueous or non-aqueous liquids.

[0096] As shown in FIGS. 7 and 12, the cover 108 is provided over thetest strips 12.4 and protects such strips from contamination. The coverincludes a plurality of first and second windows 136 and 138,respectively. First windows 136 are provided over the assay region 127of the test strips 124 while second windows 138 are provided over thecontrol region 129 of the test strips. In one embodiment, a transparentcovering 140 is provided to enable viewing of the windows 136 and 138without contamination of the test strips.

[0097] As described previously, an air outlet (not shown) is preferablyprovided on the cap to dissipate any pressure which may build up as theliquid moves along the test strip and deposited in second wick pads 130.Such air outlet may comprise a gap along the perimeter of the covering140, or one or more holes therein. In one embodiment, the cover 140 isomitted thereby exposing the cover 108 of the cap. In such case, thetest strips are exposed to the outside by means of windows 136 and 138which, therefore, provide the air outlet for the device. In anotherembodiment, an outlet for the air being displaced during the assay maybe achieved by providing one or more holes 154 in the bottom wall 115 ofthe middle portion 106. Such holes will allow the passage of air whilepreventing passage of the liquid (due to its surface tension)therethrough. In such arrangement, the holes in the wall 115 will allowthe displaced air to enter the well 110 thereby avoiding the necessityfor air outlets exposed to the outside. Such holes will therefore resultin a sealed container and avoid the possibility of the liquid leakingtherefrom.

[0098] A valve member, or seal pad 142 is provided between the base 102and the middle portion 106. The seal pad 142 is positioned within aspace 144 bounded by the wall 116 of the base 102 and an opposingbearing surface 146 formed by a plurality of indentations 148 formed inthe middle portion 106 of the cap as shown in FIGS. 1 and 13. The space144 for the seal pad is also bounded by oppositely facing comers 148 onthe top surface of the base 102 as shown in FIGS. 7 and 8. Such comersprevent movement of the seal pad 142 by engaging the lower comersthereof. To further immobilize the seal pad, there may be providedfurther comers etc. The seal pad 142 is placed adjacent the window 114on wall 116. The seal pad is generally made of a swellable materialwhich absorbs the liquid entering the well 110 and begins swelling. Asthe seal pad 142 expands, bearing wall 146 forces the pad against theopposite wall 116 and, therefore, against the window 114. It will beappreciated that the wall 116 and, the comers 148 and the upper wall 115force the seal pad to expand only in the direction of the window 114.Upon expanding a sufficient amount, the seal pad 142 thereby closes thewindow 114 and prevents further liquid from entering the well 110 andeffectively seals the liquid contents of the container fromcontamination. In the preferred embodiment as shown in FIG. 7, the wall116 is sloped and the bearing surface 146 is parallel to same. In sucharrangement, when the container is in the upright position, the seal pad142 rests upon the wall 116, and, therefore against the window 114.Similarly, when in the upside down position, the seal pad, when in thenon-expanded form, rests against the bearing surface 146. In thepreferred embodiment, the wall 116 is angled at 30°.

[0099] As shown in FIGS. 7 and 14, the seal pad 142 is laminated andcomprises of first and second layers 150 and 152, respectively. First,or sealing layer 150 is preferably a foam material such as cross-linkedpolyolefin foam. The second, or expanding layer 152 is formed from anabsorbent and expanding material. Preferably, the material forming thesecond layer 152 undergoes an irreversible expansion whereby itsexpanded form is maintained when the absorbed liquid is evaporated overtime. The choice of the material for the second layer 152 will dependupon the nature of the liquid being assayed. In the case of an aqueousliquid, the preferred material for such second layer is balsa wood. Itwill be appreciated that some materials cannot be used for certainassays as they may bind with the analytes being tested and, therefore,render a false negative result. The material for the first layer 150 ischosen to provide an adequate seal to close the window 114 and, thereby,preventing liquid from entering or leaving the well 110.

[0100] It will be appreciated that the thickness of the seal pad dependsupon various factors. For example, a pad that is too thick afterexpansion will seal the window before a sufficient volume of the liquidis collected in the well. Similarly, a pad that is too thin afterexpansion will not effectively seal the window. Therefore, the thicknessof the seal pad is based on the swellability of the pad material and thewidth of the space 144 in which it is placed. For example, the followingtable illustrates the swellability of various materials which may beused in forming the seal pad: Material Condition Swelling PEBAX Natural18% PEBAX Natural 18% PEBAX Natural 17% Balsa wood Natural  3% Balsawood Hot pressed 31% Balsa wood Hot pressed (with foam layer)  8% Balsawood Hot pressed (with foam layer)  8% Balsa wood Cold pressed (withfoam layer) 36% Balsa wood Cold pressed (with foam layer) 37%

[0101] In a cap for a conventional container, a seal pad, as shown inFIG. 14, is a total of 0.125″ in width, and has a sealing layercomprised of cross linked polyolefin of width 0.03″ and an expandinglayer comprised of balsa wood of width 0.095″. Further, in the case ofbalsa wood being used as the expanding layer, full swelling of the sealpad normally takes approximately 15 minutes.

[0102] In a preferred embodiment, the various portions of the cap 100,the base 102, the middle portion 106 and the cover 108, are attachedtogether by conventional means. In such manner, the variousnon-structural elements, the wick 120, the wick pads 128 and 130, thetest strips 124 and the seal pad 142, are maintained in a fixedposition.

[0103]FIG. 16 illustrates the positioning of the cap 100 on aconventional container 200 for specimens containing liquid 202 to betested.

[0104] In another embodiment, a raised portion 156 is provided on theside wall 116 on the surface facing the seal pad 142. Raised portion 156serves to prevent the seal pad from floating upwards against window 114while the well 110 is being filled. Such raised portion is not, however,so large as to prevent closure of the window after expansion of the sealpad. During the swelling of the pad, the flexible nature thereof willsurround the raised portion 156.

[0105] The use of the assay device of FIG. 7 is similar to thatdiscussed above. Firstly, the cap is removed and a volume of the liquidto be tested in added to the container. The cap 100 is then replacedonto the container. When the assay is required, the container in theclosed position is turned upside down thereby causing the liquid tocollect on the cap 100 and enter the inlet portion 112 of the base 102.The liquid then passes through the window 114, over the seal pad 142 andonto the top wall 115 of the well 110 where it is collected. It will beappreciated that the top wall 115 prevents the liquid sample fromcontacting the test strips 124. While the top portion of the well 110 isfilling, the seal pad gradually expands and, as discussed above,eventually seals window 114 thereby preventing further liquid fromentering the well 110. Also as mentioned above, the window 114 ispositioned a sufficient distance from the bottom surface 115 of themiddle portion 106 so that a sufficient volume of liquid can becollected within the well.

[0106] After the window is sealed, the container is turned right side upand the collected liquid 111 is maintained within the well 110. As willbe appreciated, a smaller volume of liquid will be collected within thewell if the window 114 is close to the bottom wall 115, that is, theupper surface of the well, than if the window is closer to the bottomwall 113 of the well.

[0107] The wick 120 is then allowed to absorb the liquid and, bycapillary action, transfer such liquid to the first wick pad 128. Theliquid is then transferred, again by capillary action, across the teststrip 124 and is collected at the second wick pad 130. As mentionedabove, the test strip is treated with various reagents depending uponthe assay being conducted. Further, in the preferred embodiment, aplurality of different test strips can be provided on the cap 100thereby permitting various assays to be simultaneously conducted on agiven sample.

[0108] In a preferred embodiment, the position of the window along thewall 116 can be determined based on the volume of liquid to becollected. As mentioned above, if the window is positioned close to wall115, a lesser volume will be collected than if the window is positionedclose to the bottom wall 113 of the well. Therefore, it is possible topre-determine the volume of the sample collected by the appropriatepositioning of the window. Further, in the preferred embodiment, thewindow is positioned above the bottom of the chamber 118 when in theupright position. In such arrangement, when the reservoir is beingfilled, the liquid sample level will be maintained below the opening ofthe wick chamber 118 thereby preventing the liquid from contacting thewick. Therefore, with this type of arrangement the wick is wetted, andthe assay begun, only after the device is turned upright.

[0109] As discussed previously, the embodiment described above can beused in various applications where testing of a liquid is required. Forexample, the device can be used for analyzing body fluids such as urinefor the presence of various substances. Similarly, the device can beused for testing of water samples for pollutants, toxins and other suchsubstances.

[0110] It will be appreciated that the volume of liquid collected withinthe reservoir will be dependent upon the number of test strips containedwithin the assay device since each strip absorbs a volume of the liquid.Therefore, a device having one strip will require less of a liquidsample than a device having five strips as shown in the drawings of thepreferred embodiments. The volume of the sample collected in thereservoir is based on various criteria. For example, as mentioned above,the positioning of the window 114 along the wall 116 is one such factor.In addition, the depth of the reservoir would also affect the quantityof the liquid available for the assay procedure.

[0111] In a further embodiment of the invention, the container is sealedthereby preventing leakage of the liquid contents and is provided withholes in the middle portion 106 as described above. In this embodiment,the seal pad 142 is omitted. Such a version of the invention can beutilized where a segregation of the liquid in the container and thatbeing assayed is not required. An example of such use is in the testingof samples from bodies of water.

[0112] A further embodiment of the present invention is illustrated inFIGS. 17 through 20. As with the embodiments previously discussed, theassaying device includes a container (not shown) as described above. Acap for the container is generally shown at 300.

[0113]FIG. 17 illustrates a top view of cap 300 having a generallycylindrical chamber 332 defined by inner wall 328 and outer wall 326.Positioned within the chamber 332 is a disc 346 of generally annularconfiguration having a plurality of radiating arms 348 extendingtherefrom toward the inner wall 328 of chamber 332. Inlet 360 provides apassage located between radiating arms 348 such that liquid within thecontainer passes into chamber 332 of cap 300 as described below.

[0114]FIG. 18 details the cross-sectional view of the embodiment shownin FIG. 17 along the line 1-1. The cap 300 includes a cover 314 and abase 312 preferably having a thread 304 for engaging a correspondingthread on the container as described above. The cap 300 further includesa compartment 311, and a piston 340 positioned within chamber 332. Thepiston 340 contacts the inner wall 328 and moves between a firstoperating position where inlet 360 is sealed, ad a second operatingposition where inlet 360 is open and allows contents of the container toenter the cap, as will be described below.

[0115] The piston 340 is generally cylindrical and comprises a button341 having first and second surfaces 337, 339, and a flange 343perpendicular to and extending away from the outer most edge of thesecond surface 339 of button 341. Flange 343 having an inner wall 345and an outer wall 353 includes a channel 321 formed in the outer wall353 of flange 343 having an o-ring 330 located therein. The o-ringensures a seal is maintained between the piston 340 and the inner wall328 of cylinder 332. The piston 340 further includes arm or shaft 345generally perpendicular to surface 337 of button 341 and extending awayfrom the second surface 339 of button 341. A helical spring 342 isprovided, generally coaxial with piston shaft 345, such that pistonshaft 345 extends therethough. The annular disc 346 is defined by afirst surface 347, and a second surface 349 and is diametrically opposedto button 341. Piston shaft 345 passes through a central aperture 350 ofdisc 346. Spring 342 is in compression when the piston is in the firstoperating position and bears on each of the first surface 347 of disc346 and the second surface 339 of button 341 whereby, as will bedescribed below, the piston 340 is maintained in the first operatingposition. Disc 346 further includes a plurality of radiating arms 348described above, preferably extending in all directions for connectingdisc 346 to the inner wall 328 of chamber 332. In the preferredembodiment, as shown in FIG. 17, four radiating arms 348 are provided toensure secure attachment of the disc 346 to the chamber wall 328 andalso to ensure an adequate size for inlet 360. Each of the radiatingarms 348 provide support for disc 346 such that the annulus is coaxialwith the piston shaft 345. In this manner, disc 346 and arms 348 presenta “wheel and spokes” configuration.

[0116] A valve member, or seal pad 344 comprising a generally annulardisc is defined by inner wall 331, outer wall 333, first surface 335,second surface 337 and a central aperture 351. Seal pad 344 is made of aresilient material so as to form a seal on inlet 360 whereby, when inthe first operating position, fluid is prevented from passing throughinlet 360. Piston shaft 345 passes through the central aperture 351 ofseal pad 344. A frictional fit between piston shaft 345 and inner wall331 of seal pad 344 ensures that movement of the piston arm 345 effectsmovement of seal pad 344. It will be understood by persons skilled inthe art that various other means of attaching the seal pad 344 to thepiston arm 345 are possible. A pin 336 fastened to piston shaft 345applies pressure to the second surface 337 of seal pad 344. When thepiston 340 is in the first operating position, the first surface 335 ofseal pad 344 abuts the second surface 349 of disc 346 and base 312. Theseal pad 344 extends at least the diameter of chamber 332 to the edge ofbase 312. In the first operating position, the pin 336 impinges onresilient seal pad 344 so as to apply pressure on the seat pad therebyensuring an adequate seal of the inlet 360. In the preferred embodiment,as shown in FIG. 19, the aperture of disc 346 has a greater diameterthan aperture 351 of seal pad 344.

[0117] In the preferred embodiment, the piston shaft 345, includes aterminal end 308 having a smaller diameter than the rest of shaft 345.The diameter of terminal end 308 is sufficient to frictionally engagecentral aperture 351 of seal pad 344, once terminal end 308 is passedthrough aperture 351. The diameter of the rest of shaft 345 ensures asliding fit through aperture 350 of disc 346. In this manner, a portionof seal pad 344 proximal to the central aperture 351 overlaps aperture350 of disc 346 thereby preventing any fluid from inadvertently passingthrough aperture 350 when in the first operating position.

[0118] In an alternative embodiment, the piston shaft 345 shown in FIG.18 may further include a circumferential channel (not shown) located atthe distal end of piston shaft 345 from button 341. The channel havingthe inner wall 331 of seal pad 344 located therein such that africtional fit is ensured between the channel and the seal pad 344.

[0119] In a further embodiment, seal pad 344 may have a conical shape(not shown) having a central aperture 351 as described above.

[0120] Piston 340 moves between a first operating position shown in FIG.18 and a second operating position as depicted in FIG. 19. Prior tocollecting a sample in cap 300, the container is upright and piston 340is in the first operating position and seal pad 344 maintains inlet 360in a closed state. When button 341 is depressed, piston 340 moves withinchamber 332 toward the second operating position where seal pad 344,being connected to piston shaft 345, is moved away from base 312. Spring342, on depressing the piston 340, is further compressed from itsoriginal position as shown in FIG. 18 to the position shown in FIG. 19.On releasing the button 341, spring 342 forces piston 340 to move withinchamber 332 away from opening 360, returning piston 340 to the originalfirst operating position shown in FIG. 18. As the piston 340 returns tothe first operating position, the seal pad 344 through its engagementwith piston shaft 345, also moves to the original closed positionclosing inlet 360 such that the chamber 332 is sealed from thecontainer.

[0121] The assay device of FIGS. 17-20 is used in a similar to thoseembodiments previously discussed. The cap 300 is removed and a volume ofliquid sample is added to the container. The cap 300 is replaced ontothe container. To conduct an assay, the container in the closedposition, is first inverted. Once inverted, the button 341 of cap 300 isdepressed by the user thereby moving seal pad 344 from the closed,sealed position to the open position and evacuating air within chamber332. The button 341 is then released and liquid 310 flows by gravity andsuction through inlet 360 and collects in chamber 332 of cap 300 asdepicted in FIG. 20. 0-ring seal 330 of button 341 prevents leakage ofthe liquid 310 from chamber 332 of cap 300 onto the user of the assaydevice. The piston 340 returns to the first operating position, due tothe pressure exerted by spring 342 thereby closing inlet 360. After thechamber 332 is sealed, the container is turned right side up and thecollected liquid 310, as shown in FIG. 18, is maintained in chamber 332.

[0122] As shown in FIG. 18, a first wick 321 extends along base 312 ofcompartment 311 and is preferably in the form of a rectangular slab. Oneend of first wick 321 is passed through an opening 313 in chamber 332and provides a point of contact between a first wick 321 and thecontents of chamber 332.

[0123] The cap 300 further includes an elongate wick chamber 323containing a second wick 320. The wick chamber 323 is proximal to theouter edge of the cap 300. The arrangement of elongate wick 320 issimilar to the arrangement of wick 120 shown in FIG. 7. The each of thefirst and second wick 321, 320 is made of a material which facilitatescapillary action.

[0124] Wick pad 318 is located in a first recess 322 of an upper surface315 of compartment 311. The first recess 322 is located above and opensinto the wick chamber 323 such that wick pad 318 contacts wick 320 andis wetted by same thereby drawing such liquid. In such a manner, liquid310 from chamber 332 is supplied to first wick 321 which then transfersthe liquid to elongate wick 320, to wick pad 318. Liquid absorbed bywick pad 318 contacts one or more test strips 333 and in turn transfersthe liquid to that test strip 338. The test strips 338 may be anycommonly known strip as described previously. Liquid travels along thetest strip and lastly, the test strip 338 transfers the liquid to asecond wick pad 329, located in second recess 324 on upper surface 315of compartment 311, where the liquid is collected. Pressure pads 316 aand 316 b are preferably provided proximate to the wick pads 318 and 329respectively. Test strip 338 is located between the pressure pad and thewick pad. These pressure pads not only apply pressure to the wick pad toensure contact between test strip 338 and wick pads 318 and 329respectively. The appropriate material for each of the wicks previouslydescribed is dependent upon the liquid sample and the type of testsbeing conducted. The possible materials which can form the wick werediscussed above.

[0125] As will be apparent to those skilled in the art in the light ofthe foregoing disclosure, many alterations and modifications arepossible in the practice of this invention without departing from thespirit or scope thereof. Accordingly, the scope of the invention is tobe construed in accordance with the substance defined by the followingclaims.

The Embodiment of the ivnention in which an exclusive property or isclaimed are defined as follows:
 1. An apparatus for conducting an assayon a liquid located in a container, the apparatus comprising: aremovable cap for closing the container; at least one assaying devicelocated on the cap for visual observation thereof, the assaying devicehaving means for analyzing said liquid and visually displaying thepresence of specific analytes in the sample liquid; a chamber defined byan inner and outer wall, attached to the cap and communicating with theassaying device, the chamber having a piston located therein and aninlet for collecting a volume of sample liquid inside the chamber; saidpiston contacting the wall of said chamber and moving between a firstoperating position where said inlet is sealed and a second operatingposition where said inlet is open and allows for the collection ofsample liquid is said chamber upon submergence; a means for supplyingsaid liquid collected in said chamber to said assaying device; aresilient seal pad extending at least the diameter of said chamber;whereby said seal pad, when in the first operating position, preventsfluid from passing through said inlet.
 2. A method of conducting anassay on a liquid comprising the steps of: a) collecting a sample liquidto be assayed in a container having a removable cap wherein said capincludes a chamber and an assaying device having a means for chemicallyanalyzing a liquid for a specific analyte; wherein said cap includes ainlet for connecting the chamber with said container, and a means forsealing said inlet; wherein said means for sealing said inlet includes apiston engaging a seal pad, said piston moving said seal pad between afirst closed position and a second open position; b) segregating aportion of said liquid into said chamber; c) sealing said inlet so as toprovide a hermetic barrier between said chamber and the container; d)contacting said portion of the liquid with said assaying device wherebysaid sample is assayed for said analyte.